Recherche avancée

Sur d’autres sites (8180)

• Gstreamer video increases latency with decresed FPS

  19 novembre 2024, par Ri Di

  I am using RPI 5 to stream the video :

  


  rpicam-vid -t 0 --camera 0 --nopreview --mode 2304:1296:10:P --codec yuv420 --width 640 --height 360 --framerate 10 --rotation 0 --autofocus-mode manual --inline --listen -o - | ffmpeg -f rawvideo -pix_fmt yuv420p -s:v 640x360 -r 10 -i /dev/stdin -c:v libx264 -preset ultrafast -tune zerolatency -maxrate 300k -bufsize 50k -g 30000 -f mpegts tcp://192.168.0.147:1234


  


  View it with :

  


  gst-launch-1.0 -v tcpserversrc host=0.0.0.0 port=1234 ! queue ! tsdemux ! h264parse ! avdec_h264 ! videorate ! video/x-raw,framerate=10/1 ! videoconvert ! autovideosink sync=false


  


  Problem is that with 10 FPS I get around 2s of latency ! While 56 or 120 FPS results in below 300ms latency.

  


  Is the problem in sender or reader side ? Or both ?

  


  I am not planning to use the 10 FPS, its only for demonstration of problem. But I would like to get lower latency at 56 FPS - just like at 120 FPS (around 80-100 ms difference) or maybe even better, as it seems to get lower with higher FPS.

  


  Maybe there is some kind of buffering parameter which holds frames ?

  


  (of course, when testing with higher FPS I change both numbers in sender and the one in reader command. The camera is v3 RPI official)

  


  Also I'd like to mention that same thing happens with ffplay :

  


  ffplay -i -probesize 3000 tcp://0.0.0.0:1234/?listen


  


• avcodec/mpeg12dec : Optimize reading mpeg2 intra escape codes

  8 octobre 2020, par Andreas Rheinhardt

  avcodec/mpeg12dec : Optimize reading mpeg2 intra escape codes
  Said escape code is only six bits long, so that one has at least 25 - 6
  
  bits in the bitstream reader's cache after reading it ; therefore the
  
  whole following 18 bits (containing the actual code) are already in the
  
  bitstream reader's cache, making it unnecessary to reload the cache.
  Reviewed-by : Michael Niedermayer <michael@niedermayer.cc>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavcodec/mpeg12dec.c

• Python ImageIO : Too many open files

  24 août 2017, par orbv12

  I am using imageio in python in order to open all video files in a directory and convert them to numpy arrays.

  Here is the script I am using :

    1 from __future__ import print_function
  
    2 from avi_to_numpy import *
  
    3 from os import listdir
  
    4 import numpy as np
  
    5 import imageio 
  
    6       
  
    7 class_path = '../Diving/'
  
    8 max_frames = 16
  
    9 stride = 8
  
   10 videos = [vid for vid in listdir(class_path)]
  
   11 train = []
  
   12 
  
   13 for vid in videos:
  
   14     print(str.format('Loading {}...', vid), end="")
  
   15     filename = class_path + vid
  
   16     reader = imageio.get_reader(filename, 'ffmpeg')
  
   17     frames = []
  
   18     
  
   19     for i, im in enumerate(reader):
  
   20         if len(frames) == max_frames:
  
   21             break
  
   22         
  
   23         if i % stride == 0:
  
   24             frames.append(im)
  
   25     
  
   26     reader.close()
  
   27     train.append(np.array(frames))
  
   28     print('done')        
  
   29 
  
   30 
  
   31 print(len(train))

  Eventually this script crashes with the following error output :

  Traceback (most recent call last):
  
    File "load_class_test.py", line 16, in <module>
  
      reader = imageio.get_reader(filename, 'ffmpeg')
  
    File "/usr/local/lib/python2.7/site-packages/imageio/core/functions.py", line 111, in get_reader
  
      return format.get_reader(request)
  
    File "/usr/local/lib/python2.7/site-packages/imageio/core/format.py", line 158, in get_reader
  
      return self.Reader(self, request)
  
    File "/usr/local/lib/python2.7/site-packages/imageio/core/format.py", line 207, in __init__
  
      self._open(**self.request.kwargs.copy())
  
    File "/usr/local/lib/python2.7/site-packages/imageio/plugins/ffmpeg.py", line 260, in _open
  
      self._initialize()
  
    File "/usr/local/lib/python2.7/site-packages/imageio/plugins/ffmpeg.py", line 326, in _initialize
  
      stdout=sp.PIPE, stderr=sp.PIPE)
  
    File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 710, in __init__
  
      errread, errwrite)
  
    File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 1223, in _execute_child
  
      errpipe_read, errpipe_write = self.pipe_cloexec()
  
    File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 1175, in pipe_cloexec
  
      r, w = os.pipe()
  
  OSError: [Errno 24] Too many open files
  
  </module>

  I am closing the Reader object from imageio. It seems as if the files opened by ffmpeg are not being closed properly.

  Is there an obvious step I am missing here ? Am I closing the files properly ?

  EDIT : Found temporary solution. Opened a new issue on github.

  I was able to resolve the issue by uncommenting the following lines of code from ’imageio/plugins/ffmpeg.py’ :

  381         def _close_streams(self):
  
  382             for std in (self._proc.stdin,
  
  383                         self._proc.stdout,
  
  384                         self._proc.stderr):
  
  385                 try:
  
  386                     std.close()
  
  387                 except Exception:  # pragma: no cover
  
  388                     pass

  I then added a call to the above function in _close(self) :

  271         def _close(self):
  
  272             self._terminate(0.05)  # Short timeout
  
  273             self._close_streams()
  
  274             self._proc = None

  I am not sure what the side effects of doing this are, but it provides a solution for me.

  Here is the link to the issue : https://github.com/imageio/imageio/issues/145